# US 4,396,458 A · Method for forming planar metal/insulator structures

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- Number: US 4,396,458 A
- Document ID: US4396458A
- Status: Granted
- Kind: A
- Application number: 06/333,196
- Filed: 1981-12-21
- Granted: 1983-08-02
- Earliest claimed: 1981-12-21
- Assignees: International Business Machines Corporation
- Inventors: Valeria Platter; Laura B. Rothman; Paul M. Schaible; Geraldine C. Schwartz
- Web page: https://patentgrep.com/patent/US4396458A

## CPC

- H10W 20/425: {Barrier, adhesion or liner layers}
- H10W 20/058: {by depositing on sacrificial masks, e.g. using lift-off}
- H10W 20/064: {by modifying the conductivity of conductive parts, e.g. by alloying}
- H10W 20/071: {of dielectric parts thereof}
- H10W 70/05: of insulating or insulated package substrates, or of interposers, or of redistribution layers (manufacture or treatment of leadframes H10W70/04)
- H10W 70/66: Conductive materials thereof
- H05K 3/4647: {by applying an insulating layer around previously made via studs}
- Y10S 438/951: Lift-off
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

Formation of planar conductor/insulator semiconductor devices utilizing hafnium coated aluminum based metallization with a magnesium oxide mask for dry etching of the metallization and deposition of planar insulation. The hafnium coating is used to protect the aluminum metallization during mask removal, and as a registration enhancer for subsequent electron-beam processing.

## Claims

### Claim 1

A method for the formation of a planar dielectric coating over a surface of a substrate having a conductive pattern of an aluminum based metal thereon exposing complementary portions of said substrate, comprising:
forming a hafnium coating over a portion of said pattern,
forming a magnesium oxide coating on said hafnium coating,
depositing a dielectric coating over said substrate inclusive of said magnesium oxide coating, and
wet etching said magnesium oxide coating for removal thereof together with the overlying portions of said dielectric coating thereon.

### Claim 2 (depends on 1)

The method of claim 1 wherein said substrate surface comprises a passivating coating on a semiconductor device having at least one integrated circuit therein.

### Claim 3 (depends on 2)

The method of claim 2 wherein said coating has at least one via opening for interconnection of an element of said device to said pattern.

### Claim 4 (depends on 1)

The method of claim 1 wherein said substrate comprises a ceramic.

### Claim 5 (depends on 1)

The method of claim 1 wherein said substrate is a glass ceramic.

### Claim 6

A method for formation of a planar dielectric coating over a surface of a substrate comprising:
(A) forming on said surface a lift-off mask having a pattern of openings exposing complementary portions of said surface to define a desired metallization pattern,
(B) sequentially depositing over said surface inclusive of said mask films of an aluminum based metal, hafnium and magnesium oxide,
(C) removing said mask with the overlying layers of said sequential films thereon,
(D) sputter depositing a layer of a dielectric over said substrate, and
(E) selectively wet etching said substrate to remove remaining portions of said magnesium oxide film and overlying portions of the dielectric layer thereon.

### Claim 7 (depends on 6)

The method of claim 6 wherein said substrate surface comprises a coating on a semiconductor device having at least one integrated circuit therein.

### Claim 8 (depends on 7)

The method of claim 7 wherein said coating has at least one via opening for interconnection of an element of said device to said pattern.

### Claim 9 (depends on 6)

The method of claim 6 wherein said substrate comprises a ceramic.

### Claim 10 (depends on 6)

The method of claim 6 wherein said substrate is a glass ceramic.

### Claim 11 (depends on 6)

The method of claim 6 including the additional steps of
(A) forming over the substrate of Step E of claim 6 a second lift-off mask having a pattern of openings defining at least one point of interconnection to said first metallization pattern;
(B) sequentially depositing over the surface of said substrate inclusive of said second mask, a second combination of films of an aluminum based metal, hafnium, and magnesium oxide,
(C) removing said mask with the overlying layers of said second combination of films thereon,
(D) sputter depositing a second layer of a dielectric over said substrate, and
(E) selectively etching said magnesium oxide for removal thereof together with overlying portions of dielectric thereon.

### Claim 12 (depends on 11)

The method of claim 11 including the additional steps of
(A) forming over the substrate of Step E of claim 11 a third lift-off mask having a pattern of openings defining a second conductive pattern including portions thereof over said points of interconnection,
(B) sequentially depositing over said substrate, inclusive of said third mask films of an aluminum based metal, hafnium, and magnesium oxide,
(C) removing said mask with overlying film portions thereon,
(D) sputter depositing a third layer of a dielectric over said substrate, and
(E) selectively etching said magnesium oxide for removal thereof together with overlying portions of dielectric thereon.

### Claim 13 (depends on 11, 12)

The method of claim 12 including the sequential repetition of the steps of claims 11 and 12 until the desired level of metallization is obtained.

### Claim 14

A method for formation of planar dielectric coatings over a surface of a substrate comprising:
(A) depositing a first film of an aluminum based metal over said surface;
(B) forming over said first film a lift-off mask having a pattern of openings defining a corresponding metallization pattern of said first film,
(C) sequentially depositing over said surface inclusive of said mask, films of hafnium, to form a part of said metallization pattern, and magnesium oxide,
(D) removing said mask with the overlying portions of said hafnium and magnesium oxide films,
(E) dry etching the exposed portions of said first metal film to removal thereof,
(F) depositing a layer of a dielectric over said substrate, and
(G) selectively etching said magnesium oxide for removal thereof together with overlying portions of the dielectric thereon.

### Claim 15 (depends on 14)

The method of claim 14 wherein said substrate surface comprises a coating on a semiconductor device having at least one integrated circuit therein.

### Claim 16 (depends on 15)

The method of claim 15 wherein said coating has at least one via opening for interconnection of an element of said device to said pattern.

### Claim 17 (depends on 14)

The method of claim 14 wherein said substrate comprises a ceramic.

### Claim 18 (depends on 14)

The method of claim 14 wherein said substrate is a glass ceramic.

### Claim 19 (depends on 14)

The method of claim 14 including the additional steps of
(A) depositing a second film of an aluminum based metal over the substrate of Step G of claim 14,
(B) forming over said first film a second lift-off mask having a pattern of opening defining at least one point of interconnection to said metallization pattern,
(C) sequentially depositing over said substrate, inclusive of said second mask, a second combination of films of hafnium and magnesium oxide,
(D) removing said mask with overlying portion of the hafnium and magnesium oxide films thereon,
(E) dry etching the exposed portions of said second aluminum film to removal thereof,
(F) depositing a layer of a dielectric over said substrate, and
(G) selectively etching said magnesium oxide for removal thereof together with overlying portions of dielectric thereon.

### Claim 20 (depends on 19)

The method of claim 19 including the additional steps of
(A) depositing a third film of an aluminum based metal over the substrate of Step G, in claim 19,
(B) forming over said third metal film a third lift-off mask having a pattern of openings defining a second conductive pattern including portions thereof over said points of interconnection,
(C) sequentially depositing over said substrate inclusive of said third mask and exposed portion of said third metal film, films of hafnium and magnesium oxide,
(D) removing said third mask with overlying film portions,
(E) dry etching the exposed portions of said third metal film to removal thereof,
(F) depositing a layer of a dielectric over said substrate, and
(G) selectively etching said magnesium oxide to removal thereof together with overlying dielectric portions.

### Claim 21 (depends on 19, 20)

The method of claim 20 including the sequential repetition of the steps of claims 19 and 20 until the desired levels of metallization are obtained.

### Claim 22

A method for deposition of a dielectric coating over a surface of a substrate comprising:
(A) sequentially depositing a first film of an aluminum based metal and a second metal film of hafnium over said surface,
(B) forming over said second metal film a lift-off mask having a pattern of openings defining a desired corresponding metallization pattern of said first and second films,
(C) depositing over said substrate, inclusive of said mask and the exposed portions of said second film, a layer of magnesium oxide,
(D) removing said mask and portions of said oxide layer thereon,
(E) sequentially dry etching the exposed portions of said second and first films to removal thereof,
(F) depositing a layer of a dielectric over said substrate, and
(G) selectively etching said oxide for removal thereof together with overlying portions of the dielectric thereon.

### Claim 23 (depends on 22)

The method of claim 22 wherein said substrate surface comprises a coating on a semiconductor device having at least one integrated circuit therein.

### Claim 24 (depends on 22)

The method of claim 22 wherein said substrate comprises a ceramic.

### Claim 25 (depends on 22)

The method of claim 22 wherein said substrate is a glass ceramic.

### Claim 26 (depends on 22)

The method of claim 22 including the additional steps of
(A) sequentially depositing a third film of an aluminum based metal and a fourth film of hafnium over the substrate of Step G of claim 22,
(B) forming over said fourth film a second lift-off mask having a pattern of openings defining at least one point of interconnection to said metallization pattern,
(C) depositing over said mask and exposed portions of said fourth film, a layer of magnesium oxide,
(D) removing said mask and portions of said oxide thereon,
(E) sequentially dry etching the exposed portions of said fourth and third films to removal thereof,
(F) depositing a layer of a dielectric over said substrate inclusive of said oxide, and
(G) selectively etching said oxide to removal thereof together with overlying portions of the dielectric thereon.

### Claim 27 (depends on 26)

The method of claim 26 including the additional steps of
(A) sequentially depositing a fifth film of an aluminum based metal and a sixth film of hafnium over the substrate of Step G in claim 26,
(B) forming over said sixth film a third lift-off mask having a pattern of openings defining a second conductive pattern including portions thereof over said points of interconnection,
(C) depositing over said mask and exposed metal portions, a layer of magnesium oxide,
(D) removing said third mask together with portions of said oxide thereon,
(E) sequentially dry etching the exposed metal portions to removal thereof,
(F) depositing a layer of a dielectric over said substrate inclusive of said oxide, and
(G) selectively etching said oxide to removal thereof together with overlying portions of the dielectric thereof.

### Claim 28 (depends on 26, 27)

The method of claim 27 including the sequential repetition of the steps of claim 26 and 27 until the desired levels of metallization are obtained.

### Claim 29

A process for selective removal of material from an aluminum based metal lamina of a substrate, comprising
coating said lamina with a film of hafnium,
forming a superimposed mask of magnesium oxide on said film exposing discrete areas thereof,
sequential etching exposed portions of said film and said lamina, and
removing said mask with an etchant thereof.

### Claim 30 (depends on 29)

The process of claim 29 including the step of depositing an insulator on said substrate after the etching step and prior to removal of said mask.

### Claim 31

In a process for fabrication of semiconductor devices comprised of an aluminum based layer on an insulating layer over a semiconductor substrate containing at least one integrated circuit therein, the steps comprising
depositing a layer of hafnium over said aluminum based layer,
defining a desired metallization pattern to be formed in said hafnium and aluminum based layers by a mask of magnesium oxide, dry etching exposed portions of said hafnium and aluminum based metal layers to said insulating layer, and removing said mask with an etchant.

### Claim 32 (depends on 31)

The process of claim 31 including the step of depositing an insulating layer over said substrate after said etching step and before removal of said mask.